Why should we use new , instead of virtual

nikhil kapoor

9y950Visual Basic .NET

Can anyone explain why should we use new Or when to use new and when to use virtual ,

any real life example

5 Replies

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Menaka Devi9y ago
Hi,

When to use new - if you want to hide something in the base class method.
When to use virtual - if you want to override something in the base class method.

Real Life Example :

class Nokia
{
public virtual void BatteryCapacity()
{
console.writeline("Capacity : 3000mAh");
}
public void MobileBootSound()
{
console.writeline("Nokia boot sound")
}
}
class Samsung : Nokia
{
public override void BatteryCapacity()
{
console.writeline("Capacity : 4500mAh"); //here upgrading 3000 + 1500(so 3000 is included)
}
public new MobileBootSound()
{
console.writeline("Samsung boot sound"); //here tone is totally different
}
}
class Moto : Nokia
{
public override void BatteryCapacity()
{
console.writeline("Capacity : 4000mAh"); //here upgrading 3000 + 1000(so 3000 is included)
}
public new MobileBootSound()
{
console.writeline("Moto boot sound"); //here also tone is totally different
}
}

See three mobile companies A,B&C
for ex battery capacity of A is 3000 mAh, B & C just used the same battery capacity of A and increased few mAh i.e. 3000 mAh + 1000 mAh (virtual-overriding)
But B&C instead of copy or override the boot sound of the A mobile, they implemented the new boot sound(here new - overhiding the boot sound)
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Ramesh Palanivel9y ago
Hi Nikil,

Try this URL,

It will help you!..

http://www.dotnettricks.com/learn/csharp/understanding-virtual-override-and-new-keyword-in-csharp
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nikhil kapoor9y ago
https://stackoverflow.com/questions/9590243/when-to-use-new-instead-of-override-c-sharp
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nikhil kapoor9y ago
Hi ,

That was really wonderful reply thank you so much ,

but sry being a noob i have another question

In real world, work culture and environment of all companies are same but each companies ideas,techniques should hide from each other.
virtual & override - For overriding the base class method in derived class, you have to declare base class method as virtual and derived class method as override

why can't i use new in this ? i know new will create another copy except that any other reason ?

i am baiscally clear with thier fundamental but the question is
When to use new and when to use virtual , if u can explain with any requierment :)
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Menaka Devi9y ago
Hi,

new - For hiding the base class method from derived class simply declare the derived class method with new keyword.
Class CompanyA
{
public void Techniques(){
Console.WriteLine("Company A - techniques & ideas");
}
}
Class CompanyB: CompanyA
{
public new void Techniques(){
Console.WriteLine("Company B - techniques & ideas");
}
}
In real world, work culture and environment of all companies are same but each companies ideas,techniques should hide from each other.
virtual & override - For overriding the base class method in derived class, you have to declare base class method as virtual and derived class method as override
Class CompanyA
{
public virtual void Designation(){
Console.WriteLine("Company A - employees designation");
}
}
Class CompanyB: CompanyA
{
public override void Designation(){
Console.WriteLine("Company B - employees designation");
}
}
In real world, in each companies the designation of employees may vary(i.e. software developer,system engineer but these people are doing the same work)

for further please go through this link - http://www.dotnettricks.com/learn/csharp/understanding-virtual-override-and-new-keyword-in-csharp

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